Open an internal Firebird database. Edit a new query. Try to chose an alias for one field. The alias would be ignored - the old name of the field will appear.
It's a special problem when you try to use functions, which only work in the direct SQL-mode:
SELECT "date", DATEADD(DAY,'5',"date") AS "date_new" FROM "table"
In such a query there isn't shown any name for the field, which shows the added date. The fieldname will be empty.
Take https://bugs.freedesktop.org/attachment.cgi?id=87557 for testing.
Same works with the internal database in the same version of LO.
Same works with the external Firebird database in LO 4.1.1.

Created attachment 109137[details]
Open the query - one field without fieldname
When you run the query1, you could see one field without any fieldname. This field shows the same content as the next field.
Open the query for editing. There are two fields with an alias: "Datum" AS "Date" and DATEADD(DAY, '5', "Datum") AS "NewDate". No alias is shown. "Datum" is shown for the third column and nothing for the fourth column.

(In reply to robert from comment #1)
> Created attachment 109137[details]
> Open the query - one field without fieldname
>
> When you run the query1, you could see one field without any fieldname. This
> field shows the same content as the next field.
>
> Open the query for editing. There are two fields with an alias: "Datum" AS
> "Date" and DATEADD(DAY, '5', "Datum") AS "NewDate". No alias is shown.
> "Datum" is shown for the third column and nothing for the fourth column.
Sorry for my newbieness, but maybe it will be good to have "explain like I'm five" -style instructions for this: when I open the db and try to edit the query I get this error:
The connection to the data source "Firebird_intern_query_no_alias" could not be established. SQL Status: HY000 The connection to the external data source could not be established. No SDBC driver was found for the URL 'sdbc:embedded:firebird'.
What should I do to make it work?

(In reply to Beluga from comment #2)
>
> The connection to the data source "Firebird_intern_query_no_alias" could not
> be established. SQL Status: HY000 The connection to the external data
> source could not be established. No SDBC driver was found for the URL
> 'sdbc:embedded:firebird'.
Could be you haven't enabled internal firebird. Go to
Tools → Options → LibreOffice → Advanced → Enable experimatenal features
This should start the internal firebird for LO.

(In reply to robert from comment #1)
> Created attachment 109137[details]
> Open the query - one field without fieldname
>
> When you run the query1, you could see one field without any fieldname. This
> field shows the same content as the next field.
>
> Open the query for editing. There are two fields with an alias: "Datum" AS
> "Date" and DATEADD(DAY, '5', "Datum") AS "NewDate". No alias is shown.
> "Datum" is shown for the third column and nothing for the fourth column.
Ok, I ran the query on Linux and I see what you are describing: Datum for 3rd column and nothing for 4th.
Version: 4.3.2.2.0+
Build ID: 4.3.2.2 Arch Linux build-1

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Have tested it again while creating a view:
The alias for a field will be created, if I create a view from a query, which doesn't show the alias.
See bug76072.
... but the alias wouldn't be shown through the query-GUI.
Tested with:
Version: 5.3.0.0.alpha1+
Build ID: 5d39c2013374727b1c8f147b8b99d54402a7ff02
CPU Threads: 4; OS Version: Linux 4.1; UI Render: default; VCL: gtk2; Layout Engine: old;
TinderBox: Linux-rpm_deb-x86_64@70-TDF, Branch:master, Time: 2016-11-02_00:55:24
Locale: de-DE (de_DE.UTF-8); Calc: group

Robert: would it be possible to attach a file with Firebird 3.0 format?
Indeed, I tried gbak conversion suggested in https://wiki.documentfoundation.org/Development/Base/FirebirdSQL
but gbak version provided by Debian is from Firebird 3.0 (not 2.5 one)
I suppose it's because of this version mismatch that
gbak -backup firebird.fdb firebird.fbk
gives:
gbak: ERROR:Unable to complete network request to host "localhost".
gbak: ERROR: Failed to establish a connection.
gbak:Exiting before completion due to errors

After having installed firebird-server, I got the same initial error with gbak:
gbak: ERROR:unsupported on-disk structure for file /home/julien/lo/bugs/70506_firebirdrobertalias/test/database/firebird.fdb; found 11.2, support 12.0
gbak:Exiting before completion due to errors

I installed Firebird 2.5 (superclassic) from Jessie Debian repo.
Now I've got this:
gbak: ERROR:operating system directive open failed
gbak: ERROR: Permission denied
gbak:Exiting before completion due to errors
I gave a try to http://www.firebirdfaq.org/faq102/ but nothing.
I confirm a webservice which would convert a odb with Fb 2.5 to an odb with Fb 3.0 could be very useful! :-)

If I run the query, here is the header line:
ID Name Datum DATEADD DATEADD
And here are the console logs:
warn:connectivity.firebird:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1485: Not yet implemented
warn:legacy.osl:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1489: Not implemented yet!
warn:connectivity.firebird:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1485: Not yet implemented
warn:legacy.osl:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1489: Not implemented yet!
warn:connectivity.firebird:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1485: Not yet implemented
warn:legacy.osl:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1489: Not implemented yet!
warn:connectivity.firebird:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1485: Not yet implemented
warn:legacy.osl:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1489: Not implemented yet!
warn:connectivity.firebird:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1485: Not yet implemented
warn:legacy.osl:12464:1:connectivity/source/drivers/firebird/DatabaseMetaData.cxx:1489: Not implemented yet!
warn:connectivity.firebird:12464:1:connectivity/source/drivers/firebird/ResultSetMetaData.cxx:177: Column 'DATEADD' not found in database
warn:connectivity.firebird:12464:1:connectivity/source/drivers/firebird/ResultSetMetaData.cxx:177: Column 'DATEADD' not found in database